High-Flux Oxygen-Transporting Membrane Pr0.6Sr0.4Co0.5Fe0.5O3-δ: CO2 Stability and Microstructure

High oxygen permeability and good thermochemical stability of oxygen-transporting membranes (OTMs) are two main requirements concerning the applicability of these devices in chemical processes, such as CO, capture using the oxyfuel concept or catalytic membrane reactors. In this work, a single-phase perovskite-type membrane Pr0.6Sr0.4Co0.5Fe0.5O3-delta (PSCF) with 0.6-mm thickness was subjected to periodic thermal cycling in the temperature range between 850 and 1000 degrees C in a 1000-h long-term permeation test with pure CO2 as the sweep gas. The results of this long-term permeation operation revealed a stepwise increase in oxygen permeation values at 1000 degrees C after each thermal cycle, reaching from 1.38 cm(3) (STP) min(-1) cm(-2) in the first cycle to 1.75 cm(3) (STP) min(-1) cm(-2) in the fourth cycle. Furthermore, the membrane showed very good CO2 stability at 900 degrees C and above. Despite a partial decrease in oxygen permeation fluxes at 850 degrees C, a steady state of 0.25 cm(3) (STP) min(-1) cm(-2) was reached and maintained for more than 100 h. The newly developed PSCF membrane also exhibited a higher oxygen permeation flux with He and CO2 sweeping at all measured temperatures compared to a similar La0.6Sr0.4Co0.8Fe0.2O3-delta (LSCF) membrane.